National Grid owns the high-voltage electricity transmission network in England and Wales and operates the system across Great Britain.  This comprises: 

• Nearly 9,000 circuit miles of
  high-voltage overhead line
• 420 miles of underground
  cable
• 200 supply points to distribution
  companies and large users
• 337 substations at around
  240 sites
  

We also own and operate the high pressure gas transmission system in Britain, which include:

• 4,300 miles of high pressure pipeline
• 7 coastal terminals
• Connection to eight
  distribution networks
• 26 compressor stations

Furthermore, our gas distribution business delivers gas to 11 million homes and businesses.  Key facts include:

• 82,000 miles of distribution pipelines
  Distributes gas on behalf of gas shippers and suppliers
• Network covers just over a quarter of Great Britain
• Operates the free national gas emergency number: 0800 111 999

Additionally, we have a number of related businesses in the UK including LNG importation and storage, land remediation and metering.

In the US, National Grid owns and operates electricity transmission in the northeastern US, which comprises:

• Over 10,000 miles of electricity
  transmission network
• 420 miles of underground
  cable
• A 139 mile direct current
  transmission line
• 680 substations 

We also distribute electricity to nearly five million customers in Massachusetts, New Hampshire, New York and Rhode Island, across a network of 122,000 circuit miles. 

Moreover, we are the largest distributor of natural gas in the northeast US,  delivering gas to 3.4 million customers via nearly 32,000 miles of main and distribution pipe.